1. Field of the Invention
The present invention relates to a ballast tamping machine mounted for mobility in an operating direction on a railroad track comprising two rails fastened to ties supported on a ballast bed, which comprises a tamping head comprising pairs of vibratory tamping tools immersible in the ballast and reciprocable in the operating direction and opposite thereto for tamping ballast under the ties, a track lifting and lining unit preceding the tamping head in the operating direction, and a device having outlets for substantially uniformly distributing ballast.
2. Description of the Prior Art
A track leveling and ballast tamping machine of this type has been disclosed in U.S. Pat. No. 4,794,862, dated Jan. 3, 1989. The ballast distributing device of this machine comprises a ballast storage container preceding the tamping heads in the operating direction an having controllable ballast discharge chutes. A front end of the machine may carry a ballast sweeping device for sweeping up ballast or a center ballast plow to deliver the swept-up or plowed ballast to an input end of a ballast conveyor arrangement whose output end discharges the conveyed ballast into the storage container. The machine follows a ballast cleaning machine producing varying amounts of cleaned ballast for redistribution to the ballast bed, the amount of cleaned ballast depending on the amount of waste removed by the ballast cleaning machine, and the ballast distributing device compensates for these variations and thus assures at least somewhat uniform distribution of ballast for tamping by storing any excess ballast coming from the ballast cleaning machine in the container while discharging stored cleaned ballast from the container when the ballast cleaning machine produces too little cleaned ballast.
U.S. Pat. No. 4,497,256, dated Feb. 5, 1985, discloses a mobile track leveling and ballast tamping machine comprising a pneumatic arrangement for blowing ballast under the raised ties. The pneumatic arrangement comprises a ballast storage container arranged to deliver stored ballast to blow pipes immersible in the ballast bed alongside a longitudinal edge of a respective track tie at the field and gage sides of the rails. Each pipe has a tapered end defining a ballast outlet facing the tie, the outlet having a cross section only slightly exceeding that of the pipe. A metering device is arranged between the storage container and the blow pipe for metering the delivered amount of ballast.